Physics: A Family Business

Physics: A Family Business

Uncle Emilio Heads to BerkeleyWhile all this was going on, my father, Angelo, was establishing himself as a professor of ancient history. He had heard about the great advances in physics, chiefly while spending three years away from Italy in the early 1920s, one in Vienna and two in Munich. Though he didn’t fully comprehend the physicists’ achievements, he sensed the excitement surrounding the discoveries and felt, with some regret, that the future belonged with them. Despite his quite respectable career as a historian, I believe there was nothing he admired more than science, and physics in particular.

By primogeniture my father was destined to take over running the paper mill his father owned in Tivoli, a beautiful, ancient city close to Rome. But from an early age he showed no aptitude or inclination for the task. Fortunately, his slightly younger brother, Marco, had both, so my father was free to do something else. Since Italian Jews saw academics as a clear path for advancement, it is not surprising that my father’s other brother–my uncle Emilio–became a professor, too. I sometimes think that these two brothers, one born in 1891 and the other in 1905, belonged to two different generations: one never learned to drive a car, and the other was the first in his group of friends to have one. However, I also see how much alike they were, and I realize that despite their differences, each maintained a lively interest in the other’s work.

I suspect that my father felt at some level that he had failed twice, first by not running his father’s paper mill and second by not becoming a scientist. But perhaps he thought that he could recoup some of his losses by having his children become physicists. And they both did. I don’t know what message he gave my brother, but when I was a teenager he pointed me toward that future in no uncertain terms. According to him, theoretical physics was the best possible profession, because “you will be able to tell right from and wrong, and you will not have to talk to anybody you don’t want to speak to.” I am not so sure he was correct on either count, but I did follow his directive and do not regret it. I am, however, getting ahead of myself.

Though my father was already a physics fan, news from his brother in the late 1920s had clinched his admiration for the subject. Emilio had entered the University of Rome as an engineering student and probably would have continued on this path had his life not changed in early 1927, as he was turning 22. A fellow student, the son of a mathematician, told Emilio that a supposed genius named Enrico Fermi had just been selected, at only 26 (an unheard-of age for a Rome appointment), for a new chair of theoretical physics. Furthermore, since there apparently were no Rome students interested in physics, he was looking for recruits. My uncle and his good friend Edoardo Amaldi, later the leader of post-World War II Italian physics, were the first to respond to the call.

The ensuing exploits of the growing Rome group were remarkable in absolute terms but even more important for Italy, which felt, correctly, that it was lagging behind its northern neighbors in scientific research. Italians are still proud of the group’s achievements, and even today, Fermi is regarded as the only true physics genius the country produced in the 20th century. He is also arguably the only 20th-century physicist from any country to have achieved true greatness as both a theorist and an experimentalist.

Fermi’s early fame rested on his achievements as a theorist, and perhaps most famously on his explanation of a long-standing mystery: nuclear decays involving the emission of an electron. This phenomenon seemed to violate the bedrock physics principle of conservation of energy. Furthermore, how was it possible that an electron could be emitted from within the nucleus when there presumably were none there to begin with? In late 1933, Fermi was on a skiing vacation with a few members of his group. He convened them in his hotel room and, as my uncle remembers, told them he had solved the problem. This was probably the most important piece of work he had yet done, he said, and might well be the most significant he would ever do. Drawing on an idea of Wolfgang Pauli’s, he proceeded to explain his insight, showing them how a new kind of interaction would allow a neutron to decay into a proton, an electron, and a very light particle–not yet observed–that had no electric charge. The last two would escape from the nucleus simultaneously, with the neutral particle carrying away the seemingly missing energy. To distinguish the new particle from the massive neutron (neutronein Italian), he gave it the name neutrino.